The Construction Of Composite Photocatalysts Based On Metal Organic Frameworks Derivaed And Photocatalytic Performance

In the transition from fossil energy to renewable energy,it is an important way to solve energy shortage and environmental pollutants using endless solar energy-driven semiconductor to produce hydrogen and photocatalytically degrade pollutants.In this paper,a series of metal-organic frameworks（MOFs）derivative-based composite photocatalysts were prepared by annealing and phosphating treatment as precursors.The structure,composition,and photoelectrochemical properties of the composite photocatalyst were characterized,and the photocatalytic performance of photolysis of water to produce hydrogen,photocatalytic oxygen reduction to produce H₂O₂,and photodegradation of tetracycline were investigated.The main research contents are summarized as follows:（1）The N,P co-doped C-coated CoP/Co polyhedral composite co-catalyst（Co P/Co@NPC）is prepared by annealing and phosphating ZIF-67,in order to improve its photolysis of water to produce H₂ and oxygen reduction to produce H₂O₂ performance by physical grinding to modify g-C₃N₄.Compared with Co@NC,Co P/Co@NPC formed by partial phosphating has a higher carrier density and can improve the light absorption capacity and electron-hole separation efficiency of g-C₃N₄.When the phosphating time is 15 min,the obtained Co P/Co@NPC-15/g-C₃N₄ showed the highest H₂ and H₂O₂ production performance with rates of 3.74 and 9.40μmol h^-1,respectively,which were about 2.3 and 5.6 times larger than that of phosphate Co@N-doped C-decorated g-C₃N₄（Co@NC/g-C₃N₄）,and it was revealing the good stability.（2）The Mo Ni@Mo O₂ cocatalyst was prepared by the annealing of hybrid Ni（acac）₂on Mo-MOF for modification of g-C₃N₄.Among them,Mo O₂ can be used as a"container"to store electrons generated by light excitation of g-C₃N₄,and Mo Ni units attract electrons for proton reduction reactions.With the synergistic effect of Mo Ni and Mo O₂,the charge separation efficiency and H₂ production performance of g-C₃N₄are significantly improved.And the optimal H₂ production efficiency is 1.359 mmol g^-1 h^-1,which are 6.0 and 3.7 times the H₂ production efficiency of Ni/g-C₃N₄ and Mo O₂-8%/g-C₃N₄,respectively.（3）By coating tetrabutyl titanate（TBOT）hydrolysate on the surface of In-MIL-68,annealing in the air to obtain hollow In₂O₃/TiO₂,and then electrodepositing Cu₂O to obtain ternary In₂O₃/TiO₂/Cu₂O composite photocatalyst to improve its degradation performance of tetracycline under visible light.With the help of the hollow structure of the photocatalyst,the close contact between the components,and the type-II hybrid Z-scheme electron transfer path,the charge separation efficiency of In₂O₃/TiO₂/Cu₂O-600and the degradation performance of tetracycline are significantly improved.The In₂O₃/TiO₂/Cu₂O-600 had the highest photon fluence rate in degradation of tetracycline under visible light irradiation,and its apparent rate constant（k）is 0.0293 min^-1,which is 7.2 and 3.8 times of the apparent rate constants of In₂O₃ and In₂O₃/TiO₂,respectively,and it has acceptable reusability.